Env : Windows XP, gxt 1.0beta3
Padding is missing on Firefox 2/3 in a form panel. No issue on IE6. If I compare with IE6, using IE Toolbar and Firebug, I see "padding-*: 20px;" in the style attribute of the div container (div class="x-panel-body") on IE6, not on FF.
Simple code to reproduce the bug:

I tried with beta5, replacing
formPanel.setPadding(20); by
formPanel.setStyleAttribute("padding", "20px");The bug is still present on FF 2/3, no issue on IE6. Note that when I omit the HTML 4.01 Transitional DOCTYPE declaration (passing to Quirks mode), I have no issue, but I don't think this is a satisfactory solution.

I think it should support it for some reasons :
- "Support for quirks mode (...) may be dropped in future versions of GWT"
- there are potential bugs with quirks mode
- I use standard mode (and I guess some other users too) since gxt beta 1 (it was already the default mode in applicationCreator with GWT 1.5M2) so all my webapp has been tested in standard mode.